1. Field of the Invention
The present invention relates to a linear compressor, and more particularly to a linear motor structure for a linear compressor for improving the efficiency of a motor and easily assembling a lamination provided in the linear motor.
2. Discussion of the background
FIG. 1 illustrates a general linear compressor. As shown therein, a cylindrical inner case 20 is provided in a hermetic case 10, having predetermined inner space.
A cylindrical outer lamination 30 is fixed to an inner wall of the inner case 20, and a disk-type cover plate 40 having a hole in a center portion thereof is connected to an upper end portion of the inner case 20, and a disk-type cover 50 is connected to a lower end portion thereof.
An upper portion of a cylinder 60 penetrates through an opening (not shown) of the center portion of the cover plate 40, and a valve system 70 connected to a center of the upper portion of the cylinder 60 tightly covers the hole through which the cylinder 60 penetrates. In the cylinder 60, there is provided a piston 80 which compresses a refrigerant gas by reciprocation.
A cylindrical inner lamination 90 is provided on a portion of an outer circumferential surface of the cylinder 60, having a predetermined interval from the outer lamination 30.
A coil 95, as shown in FIG. 2, winds a portion of an outer circumferential surface of the inner lamination 90, and one side of the coil 95 is connected to lead wires 95a. A disk-type connecting member 65 connects the piston 80 to a cylindrical magnet paddle 85 to which a plurality of magnets (not shown) are fixed and which is provided between the outer lamination 30 and the inner lamination 90 for transmitting the reciprocation thereof to the piston 80.
Hereinafter, a linear motor M indicates the outer lamination 30, the inner lamination including the coil 95, and the magnet paddle 85 to which the magnets (not shown) are fixed.
Further, a plurality of inner coil springs 66 elastically supporting the reciprocation of the piston 80 are provided between the connecting member 65 and the inner lamination 90, and a plurality of outer coil springs 67 supporting the reciprocation of the piston 80 are disposed between the connecting member 65 and the cover 50.
A numeral 80a which has not been described is a refrigerant gas path provided along a center portion of the piston 80 for introducing external refrigerant gas into the cylinder 60.
An operation of the conventional linear compressor will be described.
First, when power is supplied to the coil 95, the magnet paddle 85 straight reciprocates between the inner lamination 90 and the outer lamination 30, and the piston 80 reciprocates between the piston 80 and the cylinder 60 in accordance with the reciprocation of the magnet paddle 85, for thus refrigerant gas is flowed into the cylinder 60 via the refrigerant gas path 80a provided in the piston 80. The refrigerant gas compressed in the cylinder 60 is exhausted through the valve system 70, and the above-described operation is repeatedly performed.
In the above-described linear compressor, there are two systems wherein the coil 95 is connected to the outer lamination 30 or to the inner lamination 90.
As shown in FIG. 2, the coil 95 molded with an epoxy coils the portion of the outer circumferential surface of the inner lamination 90, and the lead wires 95a are connected to the one side thereof.
FIG. 3 illustrates a part of the outer lamination 30. As shown therein, the outer lamination 30 is provided with a plurality of iron pieces 36 which are radially arrayed. Each iron piece 36 has an opening portion 30a having predetermined width and length in order that the coil 95 may be inserted thereto. Thus, the outer lamination 30 is connected to the coil 95 by which the opening portions 30a of the iron pieces 36 are fixed to the coil 95.
Here, the lead wires 95a are taken out between the assembly members 35 of the outer lamination 30, as shown in FIGS. 4 and 5, and connected to an external power supply.
However, the efficiency of the linear motor M is determined in proportion to the winding number of the coil 95. An entire length of the coil 95 is determined by the winding number of the coil 95. Thus, the more the coil 95 is wound, the greater resistance of the linear motor becomes, for thereby deteriorating the efficiency of the linear motor M.
On the other hand, the system wherein the coil 95 winds the inner lamination 90 will be described.
As shown in FIGS. 6, 7A and 7B, the inner lamination 90 is provided with a plurality of iron pieces 91 which are radially arrayed and of which plane sides respectively correspond to each other. An opening portion 90a is formed in each iron piece 91, and inner end portions of the iron pieces 91 are welded along a weld line 92 to maintain a round shape of the iron pieces 91. Lastly, the coil 95 winds the opening portions 90a of the iron pieces 91. A numeral 93 is a hole for receiving the cylinder 60.
In the above-described structure, as shown in FIGS. 8A and 8B, one side of the lead wires 95a is connected to one side of the coil 95 and the other side thereof is connected to a power supply terminal (not shown), and the lead wires 95a are laid between the inner lamination 90 and the magnet paddle 85.
FIGS. 9A and 9B illustrate an another example that the lead wires 95a are connected to the coil 95. As shown therein, a predetermined number of the iron pieces 91 which constitute the inner lamination 90 are partially severed, for thereby forming a guide groove 99 having predetermined width and length. The lead wires 95a are connected through the guide groove 99 to the coil 95. Here, a bending portion of the lead wires 95a may be protruded out of the guide groove 99.
However, in the system wherein the coil winds the inner lamination, heat generated during the welding process is transmitted to the iron pieces, and thus the thermal transformation unevenly extends the iron pieces. Therefore, a gap between the inner lamination and the outer lamination is extended, for thereby degrading efficiency of the motor and erroneously performing the assembling process.
Also, since the lead wires of the coil winding the inner lamination are laid between the inner lamination and the magnet paddle, the lead wires are damaged when the magnet paddle is in contact with the lead wires in the reciprocation of the magnets.